[HN Gopher] Who won the Amstel Gold Race? Human error in photo-f...
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Who won the Amstel Gold Race? Human error in photo-finishes
Author : tomglynch
Score : 473 points
Date : 2021-04-28 16:00 UTC (1 days ago)
(HTM) web link (www.tglyn.ch)
(TXT) w3m dump (www.tglyn.ch)
| PaulHoule wrote:
| I've wondered what you'd get if you put a "photo finish" camera
| on the side of a car. The perspective would be out of whack (e.g.
| a 10 m long object 20 m away looks the same length as a 10 m long
| object 2000 m away) but it would be a much cheaper sensor than
| what Google uses for street view.
| bitcurious wrote:
| If your phone has a panorama mode try taking a photo while the
| car is cruising. As a passenger obviously.
| HALtheWise wrote:
| I would be excited to see someone try that, since it would
| produce an image that is effectively a parallel viewpoint in
| one axis and a pinhole camera in the other. I doubt it would be
| cheaper than Google's street view cameras, though, since
| standard cameras and lenses are commodity equipment.
| PaulHoule wrote:
| I think I will.
|
| An ordinary camera would work if mounted rigidly to the car,
| you could shoot a video and then take out the center line
| after the fact. 55 miles/hour is about 80 ft/sec so the
| horizontal resolution is a little bit more than a foot with a
| 60 fps video, you could make out houses but not read house
| numbers.
|
| I think most webcams have a low-level interface that would
| let you read out part of the display without reading the rest
| so getting a better frame rate could be done at low cost too.
|
| I think I'm going to try taking pictures of clouds first...
| jhayward wrote:
| I believe that is essentially what airborne surveillance
| cameras (used to) do. They used a line-aperture moving film
| setup. I don't know how they accounted for the velocity of the
| aircraft.
| [deleted]
| toast0 wrote:
| Some thoughts from looking at amstel_Finishphoto_AGR21.png.
|
| a) in the horizontal axis, everything changes at 6 pixel
| intervals, I'm going to call those samples
|
| b) I count ten samples as the narrowest of the front tire at both
| the early samples and the later samples of both riders.
| (including the fringing).
|
| c) there's a two sample gap between the front of the front tire
| of the top rider and the bottom rider (pixels 835 - 840 for the
| top rider, and 823 - 828)
|
| d) there's also a two sample gap at the back of the front tire
| (pixels 355 - 361 for the top rider and pixels 343 - 348 for the
| bottom rider)
|
| I'm not invested enough to try to figure out other points of
| reference to compare, but it seems likely that if the riders were
| separated by two samples when their front tires entered the line
| of sampling, and also separated by two samples when their front
| tires left the line of sampling, that they were separated by two
| samples throughout that time. Since they would have crossed the
| (marked) finish line while their tires were being sampled, I'm
| comfyish saying the bottom rider was 2 samples behind the top at
| the finish line.
|
| If my calculation is right, each front tire took 80 samples to
| clear the line of sampling; and if it was 2000 samples per
| second, that's 0.04 seconds for the bikes to clear the camera;
| might that be enough time for the second bike to have been pushed
| forward and pulled back such that it may have won; I dunno.
|
| also e) now I've used up my evening time I had meant to do
| something else with :P
| tomglynch wrote:
| Very good analysis. I'm just wondering if a 'bike throw' could
| cause a sudden acceleration and then deceleration both within
| the time the front wheel travelled over the line. Which could
| mean the rider in 2nd may have crossed the real finish line
| first. Though it's true that this does seem unlikely and
| therefore i'd also be comfy-ish with what you are suggestion.
| sugarkjube wrote:
| Indeed there was a bike throw, and tv footage shows pidcock
| first crossing the line. So maybe the bike throw is a good
| explanation.
|
| You guys may be on to something. Maybe worth looking at the
| axis of the wheel crossing the finish?
| toast0 wrote:
| If I hadn't forgotten where I put my physics hat, maybe we
| could figure out what sort of acceleration would be needed to
| get the bottom bike ahead of the top bike, assuming the top
| bike was traveling at constant velocity.
|
| If the front hubs were easier to distinguish, I'd have liked
| to compare those, but it didn't seem clear like the tires.
| deanpea wrote:
| Very interesting write up. Given the price of photo-finish
| cameras, I wonder if there's a solution with slow motion cameras
| which could provide some margin for error as well as a better
| spectacle for viewers?
| tomglynch wrote:
| Yeah true - it would be interesting if one of the super slow mo
| cameras they use in sports would be as good at determining the
| winner.
| comex wrote:
| Well, there are slow mo cameras that go well over the 2,000
| or 3,500 FPS mentioned in the article. If oriented the same
| way, they would provide a strict superset of the information
| of a strip photography camera, since you could recover the
| strip photo by just extracting one column from successive
| frames of the video. It doesn't seem like the price is even
| particularly different. I'm not an expert, though, just
| judging based on Google results. Maybe there is some obstacle
| I'm not thinking of.
| rocqua wrote:
| Slow mo camera's produce too much data to run continuously.
| These camera's are used to determine the entire finishing
| order. They need to be running constantly.
| ska wrote:
| You could filter a lot of it out automatically - might be
| doable these days.
| tomglynch wrote:
| OP here. I think the spoke movement is probably the most likely
| to be able to work out who reached the actual finish first. That
| is based on the spoke patterns in this image:
| http://tglyn.ch/blog/images/amstel_Finishphoto_AGR21.png
|
| The curve of the spokes should mean we can determine the distance
| the rider has traveled after the photo-finish camera.
|
| I cover my other ideas in the 'Further research required section'
| about 75% of the way down the article. If you have any further
| suggestions please let me know. Tom
| jhgb wrote:
| > having it in the wrong spot means we may never know if Tom
| Pidcock's extra speed would have allowed him to make up the
| small distance in the final 26.86cm.
|
| Isn't it possible to extrapolate the movement from the last few
| frames of the image sequence?
| tomglynch wrote:
| Potentially - do you mean via the video or the photo-finish
| image? I've suggested in the article looking at when the
| wheel reaches 98% of the full height which I think is along
| the lines of what you're saying.
| jhgb wrote:
| I meant the photo-finish cameras, but nevermind, I forgot
| how these things worked. But I would expect high-speed 2D
| cameras being available today at the finish line as well.
| mnw21cam wrote:
| The shape of the curves of the spokes doesn't depend on the
| speed. If you take the picture of the wheel, and fix the aspect
| ratio so that it is circular, then the spokes will have a curve
| independent of the speed of the wheel. Speed determination is
| purely based on the aspect ratio of the entire wheel.
|
| To reason on why this might be true - consider that the bottom
| of the wheel is stationary, and the top of the wheel is moving
| at twice the speed. This is the case regardless of the speed of
| the wheel. If you rolled the wheel past the camera really
| slowly, the entire wheel would be stretched out horizontally,
| but the spokes would all be in the same arrangement.
|
| The reason for this is that the camera is a fixed position line
| scan where the variable is time only. If we switch to thinking
| about standard video cameras with a rolling shutter, then these
| have a line scan where the variable is time _and space_ - that
| is, the camera samples a scan that is moving at a known speed.
| If you have a video with a camera like this of helicopter
| blades, for instance, then you can determine the blade rotation
| speed from a single frame. But with this finish camera, that
| doesn 't work.
|
| So, to determine speed, the best possible action is to pick two
| points on the rigid body that is moving, and time how long it
| takes to pass the recording line. The further apart these
| points are, the more accurate the average speed determination
| will be. The trade-off for this is that the speed measurement
| will be the average between the time the first point and the
| second point passes the recording line, and we are only
| interested in the average speed at the point the front of the
| bike passes the line.
|
| What we can show however, as pointed out elsewhere[0], is that
| one bike was in front of the other when the front of the wheel,
| the hub of the wheel, and the back of the wheel passed the
| recording point. When the back of the wheel passed the
| recording point, the front of the wheel definitely passed the
| actual finish line, so assuming the two wheels are the same
| size then the front of that wheel passed the finish line before
| the other one.
|
| [0] https://news.ycombinator.com/item?id=26978621
| tomglynch wrote:
| Great comment! Super informative and something I had not
| properly thought about. But you're totally right, curvature
| of the spokes is based only on the fact it's rolling past the
| camera, and two wheels rolling at different speeds will
| result in the same spoke pattern.
| eCa wrote:
| Very nice write-up, it was a fun race to watch. On your future
| research, alternative 1: Instead of only looking at the width
| of the wheel, what about looking at the height/width ratio? The
| quicker wheel ought to be relatively more "squished"
| horizontally.
|
| On the other hand, with the tight margins involved, it might be
| that the ratios are not comparable due to the fact that they
| are not the same distance from the camera.
| masswerk wrote:
| I think, the spokes are a good approach, since these are
| actually objects recorded in time.
|
| However, I think @gorgoiler [1] has made a valid point
| regarding the intersection of the "finish plane" and the plane
| recorded by the camera. (On the photo shown on your blog, the
| camera appears to be mounted slightly behind the finish line,
| thus, intersecting the "finish plane" at the ideal height,
| should point to just before the finish line at ground level.
| But there isn't sufficient information in the photo to measure
| such a minimal angle, or to confirm, if there's any at all.)
|
| [1] https://news.ycombinator.com/item?id=26977975
| ernesth wrote:
| I assume the finish line should correspond to the scaffolding
| above the road that sports "Finish".
| https://www.tglyn.ch/blog/images/amstel_photofinish_camera_p...
|
| The computation by the author of the article indeed confirms
| this: https://www.tglyn.ch/blog/images/amstel_approx_line.png
|
| My point is that it is the painted line that was not correctly
| placed rather than the camera.
| tomglynch wrote:
| This would be a great question for the operator. Thanks for
| your input :)
| mvanaltvorst wrote:
| Is it just me, or is it really obvious that Wout won?
|
| https://i.imgur.com/g78YNla.png
|
| Each pixel column is a specific point in time. I added a few
| landmarks: when the front of the wheel passes the camera view,
| when the axis of the wheel passes the camera view, and when the
| end of the wheel passes the camera view. Blue for the top biker
| (Wout) and green for the bottom biker (Tom).
|
| Every single event happened earlier for Wout. Both wheels are the
| same diameter. Therefore, the entire period where the wheel
| intersected the camera view, Wout's wheel was ahead. Including
| the exact period where Wout passed the actual finish line.
|
| If Tom would have passed Wout, you would expect that the bottom
| wheel would be more "squeezed" such that the end of Tom's wheel
| would have passed the camera line earlier than Wout. Same for the
| other landmark (centre of wheel).
|
| You can add more landmarks if you want (e.g. approximate when the
| wheel passes for 25% and for 75%), but it should be clear by pure
| margin that Wout had the lead for the whole duration where the
| front wheels passed the camera view. Pretty much all the
| computation in this article was unnecessary.
|
| Amstel gold made the good call, though I agree that it was
| probably more luck.
| polote wrote:
| Your comment clearly shows that you haven't read the article.
|
| The main point of the post is that the photo you are showing is
| not the photo at the time the two guys crossed the line
| dpwm wrote:
| > Your comment clearly shows that you haven't read the
| article.
|
| This was my first thought. Then I thought about it some more,
| and became persuaded _I_ was wrong. I definitely did read the
| article.
|
| According to the explanation in the article, it's a narrow
| slice, so the back of the wheel would be photographed when
| _that_ passed the finish line, even if ~30cm out - at which
| point the front would be clearly _over_ the finish line.
|
| The point being that the wheel is bigger than 30cm. It's
| subtle, but I'm persuaded - unless I'm missing something,
| like them not having or not actually enforcing wheel-size
| regulations.
|
| I personally find it very difficult to reason about something
| that looks so much like a photograph where only vertically-
| aligned points were taken at the same time.
| xsmasher wrote:
| You don't understand his point. He states "Each pixel column
| is a specific point in time." He's saying you can observe
| when the BACK of the wheel crosses the too-early "camera
| line" and determine the winner.
|
| Unfortunately this isn't true if the camera line is not
| parallel to the finish line, which it probably was not.
| mvanaltvorst wrote:
| I think you misunderstood how a photo finish camera works.
| Please try re-watching the explanation video. The photo isn't
| a snapshot of the race at a specific time, the photo shows an
| entire interval where the top cyclers passed the finish line.
| It's like having long shutter time and a narrow slit and
| slowly moving the camera such that you get the view of the
| slit projected along the entire camera sensor.
| gameswithgo wrote:
| the rule is that the person ahead in the photo is the winner.
| doesn't matter if the photo is wrong.
| knodi123 wrote:
| side issue- the distortion of the spokes is screaming "rolling
| shutter effect", which tells me that the sensor was only read
| from one edge to another. If it was top-to-bottom, then the top
| pixels really could be older than the bottom ones, and vice
| versa for bottom-to-top scans. If it was left-to-right it's not
| clear to me whether that could cause false impressions, but
| it's certainly not a perfect representation of a discreet
| instant of reality.
| grmarcil wrote:
| It is a kind of rolling shutter effect, but you're
| misunderstanding the finish camera's design - they capture a
| single column of pixels and the horizontal axis is actually
| time. This is why the background of photofinishes is a bunch
| of streaks.
|
| https://en.wikipedia.org/wiki/Photo_finish#Strip_photography
| tomglynch wrote:
| I agree that you're probably correct that Wout did win.
| However, I don't think you've correctly lined up the center of
| the wheels, nor the rear of Wouts wheel.
|
| For the center of the wheel, Wouts looks slighty too early and
| I think due to the larger size of Pidcock's hubs it's hard to
| determine the center here too. As for the rear of the wheel,
| Wouts gum wall tyre is hard to see.
|
| So all in all, it does seem likely Wout held the lead. However,
| a well times bike throw can change a riders speed momentarily
| for a short period of time and based on the video Pidcock's
| bike throw was significantly more effective than Wouts. So
| while I'm not going as far to say Pidcock would have won, I'd
| say there is a chance Pidcock had the lead momentarily, and
| that moment may have occurred as Pidcock crossed the actual
| finish.
| [deleted]
| bjornorn wrote:
| Assuming Pidcock was in front on the actual finish line, his
| hub would have been about 5cm in front of the photo-finish
| line. That leaves about 3ms for him to finish the bike throw
| and return his hub behind Wouts hub. Seems like a stretch,
| but still a possibility :-)
|
| Maybe you could also look at how deformed the wheel perimeter
| compared to a perfect ellipse to estimate the speed at
| different points?
|
| EDIT: Or you could calculate whether it's humanly possible to
| move a bike a few centimeters forwards and back again in
| about 15ms, which I think the hypothetical bike throw must
| have been for Pidcock to be the actual winner?
| tomglynch wrote:
| The wheel perimeter idea I did suggest (cmd + f for the
| '40%' bit down the bottom of the article) but I think the
| tolerances are likely too small to do it properly. Would
| love someone to give it a go though.
| alias_neo wrote:
| Having read the entire article, I believe the point was related
| to the photo-finish camera being positioned some distance
| before what is officially the "finish line", approx 20cm+ they
| say.
|
| The argument is that if Tom was travelling faster, the distance
| could have been made up in that time, potentially for a win.
| rjmunro wrote:
| I suspsect the camera was most likely _positioned_ exactly on
| the finish line, but _aimed_ [?]20cm behind it. This implies
| the rider furthest from the camera would be given an unfair
| advantage.
|
| If it was nudged by a gust of wind or something, it seems
| very unlikely that the camera would have moved a full 20cm
| but remained parallel to the finish line.
| mvanaltvorst wrote:
| You're right, the camera was in front of the actual finish
| line.
|
| My point is that Wout was ahead for the /entire/ duration
| where the front wheel intersected the camera line. The
| wheel's diameter is bigger than 20cm, so the moment when Wout
| passed the actual finish line is included in this interval.
| Therefore, Wout was ahead when the winner passed the actual
| finish line. QED.
| alias_neo wrote:
| Got it, thanks for elaborating, I failed to understand that
| point from your initial comment.
| cameron_b wrote:
| Stated otherwise,
|
| If there was an overtake -during- the moment of the photo
| finish then one bicycle would eclipse the other. The
| overtaken cycle would be entirely longer than the
| overtaking bicycle.
|
| Line judges go for wheel contact, so for an overtaking to
| count, the -front wheel- of the overtaking rider would have
| to be fully within the front wheel of the other.
| SiempreViernes wrote:
| As long as the rider and their bike is much wider than the
| misalignment, the only effect is to shift which point in the
| picture corresponds to the moment they pass the finishing
| line.
|
| As the OP demonstrates Wout was ahead even at landmarks over
| 20 cm from the front of the wheel the only way Tom could win
| was if his front wheel physically elongated over 20 cm in
| those last milliseconds.
| usrusr wrote:
| If it was 20 cm off it might just as well have been a few
| degrees off from being perpendicular to the road/parallel
| to the line that marks the finish.
|
| The rules are the outcome of reluctant evolution since back
| in the 19th century, it's hardly surprising that the camera
| isn't necessarily considered the ultimate source of truth.
|
| (history of techno and a road cycling race on the first
| lines of hn, today it's _really_ looking as if tailored to
| mock my interests)
| rockdoe wrote:
| This analysis assumes the camera was aligned perfectly parallel
| to the finish line, but offset from it.
|
| Unfortunately, there's no reason to assume this was true.
| Almost the opposite! If the operator did set up the camera
| correctly initially, and we know the far end ended up pointing
| to the wrong panel (got a knock?), this makes it more likely it
| was skewed so as to advantage the most distant rider. And that
| was Van Aert.
| [deleted]
| mannykannot wrote:
| Supporting evidence for your point comes, I think, from the
| fact that, for each bicycle, the left end of the handlebars
| appears ahead of the right one - meaning that it crossed the
| plane of the camera view first. I don't think the wheels
| could have been noticably misaligned from straight ahead
| here, could they? - in which case, this would imply that the
| camera plane is skewed as you suggest.
|
| If this is correct, then it suggests a way to estimate, and
| correct for, the skew, as we have other photos and videos
| showing approxinately how far the riders were from each other
| and from the camera, as well as their trajectories as they
| crossed the line.
| treis wrote:
| I think this photo pretty clearly shows the winner:
|
| https://www.tglyn.ch/blog/images/amstel_barrier_closer.png
|
| The left bike is on the white paint while the right is not.
| Clear that the left one is slightly ahead of the right
| aqme28 wrote:
| Could that camera be using a horizontal rolling shutter?
| macintux wrote:
| The right wheel appears to be elevated, per another article
| they both threw their bikes forward at the finish. That would
| impact the view from this angle to the point where I don't
| see that as definitive.
| microtheo wrote:
| No, I also thought about it and found it obvious that he won.
| cycomanic wrote:
| Thanks, I was thinking about doing the same plot as you.
| Watching the race, I believe Wout even appeared to be faster
| after the finish line, if I recall correctly.
| mvanaltvorst wrote:
| The fact that the gap between the blue and green lines is
| increasing over time confirms your hypothesis.
| SamBam wrote:
| I think you're right. Stated in simpler terms, both the front
| _and the back_ of Wout 's wheel passed the line of the camera
| before the front or back of Tom's bike.
|
| Even if the camera were 10 cms off, the fact that the back of
| Wout's front wheel passed that mark before the back of Tom's
| front wheel must means that the front of his wheel was still
| ahead at that moment. (Assuming same sized wheels.)
| Havoc wrote:
| Somewhat amazing that this can't be determined reliably. As far
| as physics problems go it seems reasonably tame compared to other
| challenges out there
| mhandley wrote:
| One other possibility is that the camera was positioned in the
| correct place, but was angled slightly to the left with respect
| to the line, rather than being exactly parallel with the line. I
| don't know how they set up these cameras to ensure they're
| parallel with the line, but this seems at least as likely as
| aligning the camera parallel but in the wrong place. I'm not sure
| how you'd be able to tell from the images though, but it would
| make a much bigger difference to the actual result.
| jrudolph wrote:
| Awesome research. I have similar quibbles about photo finish
| cameras in sports and written about them [0].
|
| There are usually tons of rules in sport about the equipment, the
| Race course etc . but how exactly the finish needs to be set up
| is often vague. In this case it was an alignment issue at fault.
| But the next problem is the arbitrary resolution finish cameras
| work at. How wide is the pixel slot? This can be the difference
| between calling a tie or a small margin.
|
| [0] https://www.rowinginmotion.com/thoughts-fairness-rowing/
| tomglynch wrote:
| Yeah the UCI rules for photo finish seem very vague, and also
| don't seem enforced. I haven't used a photo-finish camera
| myself but it seems to me the tech behind these is quite dated,
| the shots from the 1960s are almost as good except for the
| frame rate and number of pixels. Perhaps there is a better way.
| scotty79 wrote:
| Or you could just change the rules and declare that the finish
| line is wherever the camera is pointed at and what's painted on
| the ground is just a rough indicator of where the finish line
| actually is.
|
| Or maybe rules are already exactly that?
| adamjb wrote:
| That is in fact what the UCI regulations say.
| sverhagen wrote:
| It's been maybe fifteen years since I read up on those rules,
| I assume some things changed, but there weren't much details
| on this then. Do you have some relevant quotes?
| tomglynch wrote:
| This is also what I thought when reading the rules. It does
| say the race if you can't tell by the eye is decided by the
| photo-finish. But from what I read at no point does it say,
| the finish is where the photo-finish points and the paint
| is just arbitrary.
| throwaway744678 wrote:
| Wouldn't it be a bit unfair for the competitors? They wouldn't
| have any way of knowing where the actual finish line would
| stand.
|
| Perhaps they could include some margin of error; if the photo
| is in that margin, the result would be a tie?
| xmprt wrote:
| This was a really good writeup. I thought for sure there would be
| no way to salvage it after you mentioned how they messed up but
| then you talked about using the curvature of the spokes and the
| width of the wheels in the photo finish to figure out how the
| wheels were spinning and it blew my mind.
| abel_ wrote:
| I think the distortion of the video-finish camera should be
| considered when making these estimates. There's quite a lot of it
| happening in the shot. Narrowing down the specific camera
| intrinsic parameters may be a challenge. The EXIF data of the
| original footage might be fruitful.
|
| It might also be possible to undistort using some assumptions on
| colinear points in the video (i.e., the finish line and signs
| should have straight lines).
| lostlogin wrote:
| > It might also be possible to undistort.
|
| It might be possible to res it right up using that new
| photoshop feature. A joke obviously...
| tomglynch wrote:
| Exif data is a good suggestion - I'll see what I've got
|
| EDIT: nah nothing interesting there. It may have been stripped
| when they emailed it to me?
| helsinkiandrew wrote:
| I'd say that was a draw.
| fotta wrote:
| I used to work with these line-scan photo finish camera systems
| (we used FinishLynx) timing track meets.
|
| This error is pretty comical to me because aligning the camera is
| the first thing we do after putting the camera up and looking at
| their images, it's pretty clear it wasn't aligned properly. The
| cameras can auto-align, but we didn't trust it and manually
| aligned it, but I'm wondering if maybe the event organizers auto-
| aligned and didn't bother to check? The cameras are mounted on a
| motorized base that can move in 3 dimensions with very fine
| precision [0]. In the OP, you can see the event organizers have a
| black line across the finish on a white base. In order to
| manually align it you just have someone run back and forth across
| the line and move the camera with the computer until you pick up
| the very left edge of the black line, which is very clear because
| you can see the ground change from black to white in the image
| (or vice versa depending on where you start).
|
| We also used to always put a white piece of wood behind the line
| so that the images would always have a white background. This
| makes it so much easier to detect the edge of a torso when
| clicking on a person to indicate their time. In the OP, if their
| camera was aligned correctly, red would've been a tough
| background color. Also a black line is questionable. I would've
| had a white line on black base for the same reasons.
|
| [0] https://www.finishlynx.com/product/accessories/camera-
| mounti...
| dekhn wrote:
| Time differences like this are insignificant.
| cycomanic wrote:
| I see on issue with this analysis, the use of the TV camera
| picture a the reference datum. However, that camera has likely
| many more issues than the finish line camera. While it looks like
| the red advertisement is aligned with the camera from that image
| I don't think this is necessarily the case. It depends on the
| height of the camera, the angle and possible distortions.
| tomglynch wrote:
| While I've only inCluded that single image in my analysis,
| having a look at the video of the full race where they pass the
| finish line many times it is clear the red sign is aligned with
| the finish line.
| cycomanic wrote:
| That's not what I mean. You assume that the TV camera is
| perfectly aligned with the finish line, because that's how
| you determine the position of the advertisement relative to
| the line. However, if the TV camera is offset from the finish
| line, depending on height/focal length/orientation and
| aberrations of the camera, the line would appear offset
| relative to the advertisement. Therefore you determine the
| wrong position of the line compared to the advertisement.
| That would always be the same for the full video of the race,
| so watching the race will not change this.
| cycomanic wrote:
| I should say that it might not make a difference, but
| mainly to point out that one needs to be careful as to what
| exactly we use as our datum.
| tsjq wrote:
| Too much work, IMO. Just give them both Gold medals.
| mariusor wrote:
| For this particular race you get beer, not medals. I don't
| remember seeing medals in cycling outside of the Olympics.
| xpe wrote:
| In addition to the technological factors here (optics), think
| about the biological timing of the riders. Wout van Aert picked
| the right time to accelerate and win -- from the front! He won
| even with a significant aerodynamic disadvantage.
|
| Wout!!!
|
| > According to UCI regulations, the photo finish verdict is
| final, because the finish line is what the photo finish says it
| is.
|
| https://cyclingtips.com/2021/04/making-sense-of-the-controve...
| gorgoiler wrote:
| The "finish line" could be thought of as a two dimensional plane.
| The winner is the first person to touch or pass through the
| plane.
|
| If you're painting a line then the "finish line" is where that
| plane touches the ground. For other races it might be a piece of
| tape held at chest height -- the part of the body that usually
| goes through the plane first.
|
| When the competitors are bicycles then they all the same height
| -- the middles of the front wheels are all the same height off
| the ground, something on the order of 400mm. The finish line is
| floating about a foot off the ground.
|
| The specialist streak camera photographs objects passing through
| a 2D plane. Ideally you would have that plane aligned vertically
| so that the finish plane and the camera plane were the same.
|
| If for some reason you couldn't do that -- let's say the camera
| could only be placed a few feet in front of the finish line so as
| to see around an object -- then you would have to _arbitrarily_
| angle the camera plane to intersect the finish plane.
|
| The intersection of these two planes will give you the "finish
| line". For a bicycle race, do you set it up so that the finish
| line is on the ground, or floating 400mm above the ground? If you
| do the latter then the projection of the camera plane into the
| road will indeed give a line that stops short of the finish
| plane, but that's irrelevant -- the actual finish line at the
| middle of the front wheel is in the correct place.
|
| I think the article assumes the former when the organisers did
| the latter?
| falcolas wrote:
| It's my understanding (and confirmed by other comments on HN to
| this article) that the rules define the camera's sensing plane
| _as_ the finish plane. So, regardless of the paint on the
| ground (which can not and will not ever form a perfect line),
| it 's the camera that matters.
| tomglynch wrote:
| Ah this is an interesting thought though I don't think this is
| what the organisers were trying to do. Or if they are, it does
| not match up with what they are meant to do as per the UCI
| specs (the UCI is the international cycling governing body).
|
| In another comment I was discussing the tech being somewhat
| outdated - perhaps your suggestion is part of the solution.
| Would two cameras on different planes result in more accurate
| results?
| gorgoiler wrote:
| It's probably quite hard to make an orthographic streak
| camera that is pointing vertically down in the same plane as
| the finish, but that seems like the optimal solution.
|
| Moreover, if the camera is used to identify the times and
| finish positions of all the riders, it's probably quite hard
| to identify them from above. Perhaps a streak video
| synchronised with TV footage would be convincing?
|
| How about a prismatic laser and fog machine at the finish?
| It'll look like an 80s rave but the streak camera will
| clearly show where the finish is.
| dmurray wrote:
| > Would two cameras on different planes result in more
| accurate results?
|
| A man with one watch knows what time it is. A man with two is
| never sure.
| reedf1 wrote:
| Doesn't the difficulty here become the limitations of the
| sensor? And perhaps lens distortion?
| FearNotDaniel wrote:
| As a child I was taught that sport should be "sportsmanlike".
| Perhaps in a situation like this, the real solution should be "I
| say, it's a draw, well done chaps, you have both proved to be at
| the top of your field! How remarkable that the result is so close
| that our best technology cannot even distinguish between the two
| of you. Well done everyone, what a great race, now let's all go
| to the pub and celebrate."
| croon wrote:
| Or have a tiebreaker. It would be testing something slightly
| different (more endurance) than what they'd train for, but
| there would likely be an easier call the second time,
| statistically if nothing else.
| rexfuzzle wrote:
| It also happens in horse racing which I though was very off
| considering the betting involved.
| Ensorceled wrote:
| The "dead heat" rules are fair, the bookies pay out half for
| both winners (or thirds for three etc.)
| timwaagh wrote:
| sportsmanlike is when you lose by a hair, you congratulate the
| winner and don't feel too bad about it. What you're suggesting
| is a test of competence, not a race.
| vbsteven wrote:
| I agree that sport should be sportsmanlike, but there is also
| an entertainment factor. These pro cyclists are public figures,
| paid by teams funded by corporate sponsors, cyclists have
| public rivalries and journalists pour fuel on the fire. Events
| from one race carry over to the next. There is lots of drama,
| there are rules which change over time (and usually lag a few
| years behind technology advances), race officials have to make
| decisions in the heat of the moment, usually very controversial
| decisions after rule changes. (look at the recent
| disqualifications due to the new anti-littering and dangerous-
| bike-position rules this year, and the bike-lane rules a few
| years ago)
|
| On one side it's unfortunate that technological details and
| possibly human error make it hard or controversial to decide
| the winner for this race, on the other side this event has kept
| the cycling community talking for 3 weeks (even HN is talking
| about it right now). And most likely in the next few months or
| years we'll see some rule/regulation changes to handle these
| cases better. Just like in politics, something needs to happen
| first before action is taken. All the recent rule changes were
| triggered by dangerous crashes or other events.
|
| And imho all of this combined makes pro-cycling one of the most
| exciting forms of entertainment to watch or follow.
|
| A little side note: Many amateur races don't have photo finish
| equipment. In my race days sometimes not even a camera, and 3
| race officials would stand on a little platform above the
| finish line with voice recorders just calling out jersey
| numbers and then get together in a room for 20 minutes to
| compare recordings and compile the final result. Draws were
| much more common back then.
|
| edit: all of the previous races and media coverage and drama
| and the first 250k in this race have led to this super exciting
| final 1k that is ultimately decided by millimeters. To me that
| is beautiful.
| eru wrote:
| > A little side note: Many amateur races don't have photo
| finish equipment. In my race days sometimes not even a
| camera, and 3 race officials would stand on a little platform
| above the finish line with voice recorders just calling out
| jersey numbers and then get together in a room for 20 minutes
| to compare recordings and compile the final result. Draws
| were much more common back then.
|
| Interestingly, technology makes this trivial these days:
|
| Pop a cheap Android phone on a tripod, and with the right
| software (or even just taking a video), you have a decent
| approximation of photo finish equipment.
|
| (I say 'trivial', because a smartphones with the required
| capabilities are basically free, if you take an old, used
| one.)
| vbsteven wrote:
| Yes indeed. And I have to admit that my race days are more
| than 10 years ago before smartphones were commonplace. The
| fancy organizers had camcorders for this purpose, others
| audio recorders and some others just pen and paper.
| inopinatus wrote:
| Transponders are very common in club level racing now, and
| the accuracy available is good enough for the grassroots
| level of competition in pretty much every discipline (except,
| possibly, track sprint).
|
| Still, I think there will always be a place for a stone-faced
| commissaire with a clipboard, freezing their ass off in the
| finish-line rain, watching the bunch draw near.
| sverhagen wrote:
| I worked in this field, posted elsewhere on this page about
| working photo finish at Amstel Gold in the past. Around
| that time we also experimented with transponders, maybe
| even at an Amstel Gold Race, else at the Netherlands Tour
| (or Eneco Tour). The accuracy, at high speed, of
| transponders, didn't quite solve for the close finishes. A
| bigger problem were the practical issues: transponders gone
| missing in crashes, bike switches, transponders being
| mounted in the wrong place (enough to matter). It's not a
| substitute for photo finish. It is, though, a great
| substitute for reading bib numbers off of a poorly lighted
| photo finish. They're complementary.
| vbsteven wrote:
| Would you be so kind to provide a short high level
| summary on how the transponder tech works?
|
| I always assumed the transponders were mostly used for GC
| timekeeping in multi-day stage races and maybe help
| automate the initial results shown on TV post-finish.
|
| The live telemetry (wattage, speed, heartrate) we've seen
| in some races the last few years are also very
| interesting. But that's probably a different tech stack
| from transponders used for timekeeping.
| inopinatus wrote:
| Most transponders in competitive sports, and certainly
| most pro cycling events, will be an active type, i.e.
| they include their own power source. The timing mats are
| relatively simple EM trigger loops that induce the
| transponder to wake up, yelp its identity (typically on
| UHF frequencies) to the trackside receivers that will
| actually record the passing time, then go back to sleep.
| Such systems generally remain reliable even in large
| passing groups. Commercial prices vary, but the trackside
| equipment (mat, decoder, laptop, software) typically
| costs a few thousand dollars, and the transponders ~$100
| each with a lifespan of 5 years.
|
| Some manufacturers claim millisecond accuracy, which is
| plenty for (say) counting laps in cyclo-cross, or for
| timing many BMX events; but they're not enough to
| distinguish the places in a >70km/h field sprint for the
| finish line.
|
| Some mass participation events like public marathons may
| use low-cost/disposable passive transponders e.g. ones
| embedded in the bib number; these are more like a typical
| RFID chip, having a longer (and rather jittery) wake-up
| time, in part because they draw power from the mat
| itself, and a much lower transmission energy. They're
| more easily disrupted by environmental conditions, or
| when passing in large groups, or even by sweat & skin
| contact.
|
| Telemetry from onboard bike computers and sensors is
| indeed a completely separate stack, and can be anything
| from a bluetooth relay by phone app over cellular, to a
| dedicated vendor-specific box with its own SIM card and a
| short-range radio to signal the team car. The onboard
| sensors are generally using ANT or BTLE to talk to the
| head unit aka "bike computer" that aggregates, records,
| displays, and relays the data. Speed may be calculated by
| GPS/GLONASS/etc, or sensed by wheel rotations e.g. using
| a spoke magnet or even hub-based rate ticker, in which
| case the necessary measure of precise wheel diameter may
| still be calibrated by the head unit using GPS. Power is
| not measured directly but inferred e.g. by integrating a
| dynamometer within the crankarm to compute power from
| strain & cadence. Some units also capture barometric
| pressure to estimate altitude, and this may be considered
| more accurate than GPS right up until you ride through a
| pressure front and it goes bananas. Some bicycles e.g.
| those with electronic/wireless shifting may also report
| their current chainring & sprocket selection, and finally
| you can overlay all this excruciating near-real-time
| detail onto the Gopro video feed from your
| handlebars/seatpost cameras and livestream it over
| cellular networks and thence to the world-wide peanut
| gallery.
|
| To sum up, there's an awful lot of 2.4GHz activity going
| on in the pro peloton, and I hereby deny ever having
| paired a second bike computer with the HR strap and power
| meter of my nemesis in order to know when the bastard was
| too tired to follow my attack, no sir
| vbsteven wrote:
| Thank you. That was exactly the information I was looking
| for.
| eterevsky wrote:
| I don't see how declaring this race a draw would deter from
| the excitement or from the entertainment value. If anything,
| it would add to it, since this is such a rare occurrence.
| foobar1962 wrote:
| The gambling/betting agencies won't want 2 winners in the
| race.
| vbsteven wrote:
| Agreed, my response was not meant as a judgement on whether
| a draw would be a better or worse conclusion. I was trying
| to highlight the broader context around the events and
| their outcome.
|
| In this case it wasn't immediately clear who won and the
| officials had to make a call under pressure with millions
| of people waiting. They called Van Aert as the winner based
| on the imperfect data they had. Was it the right call?
| Maybe, maybe not. In an alternate timeline they might have
| called Pidcock, or a draw, or a redo of the last 1km.
|
| The takeaway is that this rare occurrence happened and
| sparked lots of discussion, which hopefully leads to
| technological and/or regulation changes to could handle
| these occurrences better in the future. I would call that
| progress.
| cesis wrote:
| That happens in Olympic Games
|
| https://www.olympic.org/news/double-gold-medal-joy-as-oleksi...
| doikor wrote:
| This happens in swimming because of the tolerance of making
| an olympic spec pool. A good swimmer goes a bit over 2mm
| every 0.001s. The pools have 3cm tolerance meaning the lanes
| are not the exact same length (it would be crazy expensive to
| make pools to smaller tolerances)
|
| So to solve this they just don't measure beyond hundreds (no
| human can swim fast enough that the distance they travel
| within 0.01s could make a difference). And thus can not use
| photo finish either as again the lanes are not guaranteed to
| be the same length.
|
| https://interestingengineering.com/significant-digits-and-
| po...
|
| edit: In other sports like running it is easy to have
| accurate track length as you just paint the lines after
| building the track so you can have it as accurate as you want
| (+photo finish). In swimming it just does not work like that.
| Ichthypresbyter wrote:
| Exactly- in a few days earlier, Mahe Drysdale of New
| Zealand won gold in the men's single sculls after being
| maybe a centimetre ahead of Damir Martin of Croatia at the
| line:
|
| https://www.telegraph.co.uk/content/dam/news/2016/08/13/dry
| s...
|
| (Drysdale is in the black boat).
| eru wrote:
| Well, they could have everyone swim one after another in
| the same lane. It's not like there's much interaction
| between racers, as there is eg in a boxing match.
|
| (Of course, this would totally ruin the sport for
| spectators.
|
| Following this logic, for any sport with no interaction,
| everyone could just stay home and run around their own
| track whenever they feel like and just send in their times
| to a central record keeper.)
| xxs wrote:
| Having a competitor next to you provides a stronger
| absolute result. It's believed to be a standard natural
| selection/evolution effect. Even pain tolerances
| increase.
| usrusr wrote:
| Also conditions change over time. Indoor pools are much
| less affected than e.g. a ski run in inclement weather or
| ski flying where competitions are basically lotteries in
| who gets a favorable gust, but subtle changes in e.g. air
| oxygen content could easily cause performance differences
| in the range we are talking about here.
| xxs wrote:
| >ski flying where competitions are basically lotteries in
| who gets a favorable gust
|
| That has always bothered me that there are some
| calculations/arbitrary numbers based on the wind... to a
| point the length of the ramp gets adjusted. I recall when
| the V shape was introduced, initially it was shunned by
| the judges for bad style (negative points), regardless it
| was obviously aerodynamically better. However, swimming
| would also be affected as the water temperature won't be
| constant either.
| Someone wrote:
| That still doesn't guarantee that the winner was the
| fastest.
|
| Let's say real times were 58.994999 and 58.995000 seconds.
| The first gets registered as 58.99, the second as 59.00.
| Actual difference is a millionth of a second, or, at 2
| meters a second, 2mm.
|
| I think they do this in swimming more because swimmers,
| certainly at shorter distances, more race themselves than
| their competitors. That's a huge difference with road
| cycling, where typically the front riders in a sprint could
| get over the finish earlier, if they wanted to, but don't
| want to do that, as, if they did that, their competition
| would tail them up to the last few meters and then jump
| over them.
|
| Rowing is somewhat of a middle ground. They do use finish
| photos, even though there's the same. "Tracks aren't
| guaranteed to be the same length" problem as in swimming.
|
| A famous example is the men's scull final in the 2016
| Olympics:
| https://www.olympicchannel.com/en/video/detail/mahe-
| drysdale...
|
| I don't understand why you think it's easy to have accurate
| track length in running. Temperature may affect track
| length. A lot more importantly, I don't think it's even
| doable in events where runners all start in their own track
| but are allowed to move to the inner track after x meters.
| But again, it's less important there because runners race
| against each other there more than in short swim races.
| xxs wrote:
| >Let's say real times were 58.994999 and 58.995000
| seconds.
|
| How do you achieve a million frames per second? Even
| analog input (like touching - which would be capacitive
| [hence more tolerances]) will have a very hard time
| registering that, just based on cable and PCB traces
| length, temperature differences (which affect silicon and
| resistance in general). 7 digit precision is a non-
| trivial task for non-controlled environment. For example
| 8.5 digit voltmeters take one 1 minute for a single
| measurement and they have to have extremely good
| temperature controls.
|
| Then for the microsecond precision you have to consider
| the speed of sound just to propagate to participants to
| hear the gun.
| sokoloff wrote:
| They're not hypothesizing a measurement device recording
| those times and then rounding. They're just setting up a
| "let's take as a given that this is what really happened
| in the world" and asking what errors our processes could
| do if we do a series of imprecise measurements and then
| compare those measurements.
|
| Side note: my HP 3458A can do a small handful of 8.5
| digit DCV measurements per second.
| xxs wrote:
| >my HP 3458A can do a small handful of 8.5 digit DCV
| measurements per second.
|
| I thought they had like 100k samples a second. Is it
| really sufficient for 8.5 precision?
|
| Edit: perhaps measurement should be confined only to
| relative finish between the participants, e.g. finish
| within 1ms should be considered the same (regardless if
| they fall in the same hundreds of a second bucket)
| cameron_b wrote:
| interestingly enough, for stage races, that is how things
| work to some degree for the "pack" finish, just not the
| guys going for the day's podium
| sokoloff wrote:
| I don't keep mine in cal (or even powered up all the
| time), so I can't claim full volt-nut status here, but my
| understanding is the 100K/sec 4.5 digit measurement rate
| is limited by communications not by sampling rate. (The
| 5.5 digit rate is 50K/sec, implying the 4.5 digit rate
| limit is not in the measurement but more likely in the
| GPIB.)
|
| On thing I know with perfect precision: HP/Keysight knows
| more than me about this. :)
| Ichthypresbyter wrote:
| Rowing alignment is slightly different from swimming
| alignment.
|
| In swimming, the start and finish are both fixed physical
| objects that the swimmer must touch (though in all events
| except backstroke, the start is a bit weird because it's
| outside the pool).
|
| In rowing, the finish line is an imaginary line much like
| cycling or running. While at the Olympics there are
| 'clogs' to hold the bows of the boats which drop down at
| the start:
|
| https://www.polaritas.com/products-and-
| services/automatic-st...
|
| a race official is always required to certify that the
| bows are aligned, which is why the gates are transparent
| (and the system includes video cameras to help this
| official).
| doikor wrote:
| > "Tracks aren't guaranteed to be the same length"
| problem as in swimming.
|
| In rowing you row between 2 imaginary lines. You don't
| even have to get the distance of these lines perfectly
| just make sure they are both in the same direction and
| neither boat gets the advantage.
|
| With swimming you have to build a 50m long and quite wide
| concrete structure that has straight angles at all 4
| corners and has perfectly straight walls. This is
| actually much harder to do then it sounds.
| stevesimmons wrote:
| We could do it in swimming by building the pools a few cm
| longer, and then having adjustable touchplates to give
| the precise distance for each lane. :)
| doikor wrote:
| This is actually how it is done for new pools. They
| overbuild them by a couple cm and then adjust the
| touchplates. But the rules should work for the 50y old
| pools too.
| Someone wrote:
| > You don't even have to get the distance of these lines
| perfectly just make sure they are both in the same
| direction and neither boat gets the advantage.
|
| Nitpick: that is not correct. If the shape of the course
| is a parallellogram, the shortest course between the
| short sides is perpendicular to those sides. Teams in
| some of the lanes my be able to pick such a course. For
| example:
| ________________________________ /A
| B/ / /
| / / /C
| D/ -----------------------------------------
| -------------------
|
| A crew starting in the AB lane can row to D instead.
| That's legal, if they don't hinder other crews. A crew
| starting at C doesn't have the option to row a shorter
| course.
|
| It is very unlikely they won't hinder other crews if they
| cross all lanes, but they might just cross lanes of a few
| much slower boats.
|
| That's all theoretical, though. The net gain on a normal
| course would be very, very small, and buoys will
| typically hinder crews that would try this so much that
| it wouldn't be worth it, to start with.
|
| Also, for the true nitpicker, "the right direction" can
| be difficult. Drawing equidistant lines on a globe isn't
| trivial (I don't think the effect will be large for a 2km
| course on earth, though)
| tzs wrote:
| > This happens in swimming because of the tolerance of
| making an olympic spec pool. A good swimmer goes a bit over
| 2mm every 0.001s. The pools have 3cm tolerance meaning the
| lanes are not the exact same length (it would be crazy
| expensive to make pools to smaller tolerances).
|
| It would be crazy expensive to make the _pools_ to such a
| small tolerance, perhaps, but it is not the length of the
| pool that actually counts, is it? It is the distance to the
| touch pad that counts.
|
| Would it be crazy expensive to make the touch pad mounting
| system adjustable so that the position of each lane's pad
| could be adjusted to millimeter or even sub-millimeter
| tolerances?
| doikor wrote:
| Main problem is old pools that don't have space for this
| (would make the pool under length). In general the same
| rules are used in all levels of competition. The only
| difference at the moment is minimum pool depth for world
| championships and olympics which is a bit deeper.
|
| But yes in general new competition pools are built to be
| slightly larger than 50m and you just adjust the pads at
| the ends.
| toast0 wrote:
| Many swim races are more than one lap, so you would have
| to adjust the touch pads for lap count.
| opwieurposiu wrote:
| You could equalize the length of the lanes, but there are
| water currents that give different lanes "headwinds" or
| "tailwinds". These are caused by the pumps, wave action,
| and thermal convection.
| xxs wrote:
| Swimming is worse than that as the inner lanes have
| inherent advantage of less water drag as the waves bounce
| off the walls. Of course inner lanes are seeded with the
| fastest timings from the previous heat.
| doikor wrote:
| This is why modern competition pools are 10 lanes wide
| but only the inner 8 are used in competitions.
| runningmike wrote:
| Great research! But van Aart is the right winner. The photo
| finish picture is stated s the official result. Every athlete
| knows that, despite alignment errors of the equipment.
| djmips wrote:
| Exactly. It's a bit arbitrary but it's the final call.
| viraptor wrote:
| The idea of the race, bikes, and how we measure the whole
| thing is arbitrary to begin with :-)
| tomglynch wrote:
| True, though if Wout won by the rules but Tom crossed the
| finish line first that is not a great outcome.
| hiroprot wrote:
| Given that they are not necessarily the same, perhaps more
| accurate to say "So who crossed the finish line first?" in
| your article? We know who won.
|
| As someone who has both won and lost bike races determined by
| photo finish, I enjoyed this article a lot. Well done sir!
| MR4D wrote:
| Fascinating article, and great to see a problem solver at work.
|
| However, I question humanity's sanity when we declare a winner in
| a 216.75km long race by someone who (possibly) won by 0.016
| seconds (and poorly declared either way from the article).
|
| At what point do races become a tie instead of 1st/2nd ? Just
| because we can doesn't mean we should. I mean, if we had a camera
| that could take 350,000 photos per second does that mean we
| should use it to declare the winner?
|
| I remember this issue came up in swimming a few years ago, and
| people were arguing that the timing measurement was finer than
| the tolerance for error of the measurement of pressure on the
| pad. We still talk about that race venue today:
| https://www.theringer.com/2020/7/29/21345181/milorad-cavic-m...
|
| This article seems to make the argument quite well:
| https://olympics.time.com/2012/07/27/technologys-touch-how-a...
| tcmb wrote:
| With regards to swimming, I once read they measure times only
| up to hundredths of seconds, because the individual lanes of
| the pool cannot be built to be the same length within a margin
| of error that would warrant measuring times more accurately.
|
| https://deadspin.com/this-is-why-there-are-so-many-ties-in-s...
| ArnoVW wrote:
| Same reason why in athletics the starter pistol sound is
| transmitted via a speaker behind each individual lane.
| Otherwise the speed of sound would disadvantage the lane
| furthest from the starter pistol by more than a hundredth of
| a second.
| f137 wrote:
| Thanks, I was wandering how they account for the speed of
| sound but was lazy to google )
| Cerium wrote:
| They could just trigger the starter from a long distance
| behind or in front of the line instead.
| blackboxlogic wrote:
| If the starter pistol is too far away, there's a chance
| to see the smoke before hearing it.
| ASalazarMX wrote:
| Or use a visual cue. I've always wondered why they need a
| pistol.
| mikestew wrote:
| Sprinters, for whom small margins make the biggest
| difference, are most often not looking at the starter.
| Granted, could be because they don't have to because
| someone is firing a .32 caliber blank nearby, but that
| horse has left the barn for now.
| benzor wrote:
| Interesting factoid: the human brain processes sound
| faster that sight [1]. The difference cited in the paper
| below is roughly 40 ms, which is small in an absolute
| sense, but compared to the relative time tolerances we
| are discussing here in this parent article, it's huge!
|
| Naturally this effect cancels out if all competitors get
| the same visual cue, however it's still to the benefit of
| athletes and fans to want quicker reaction times:
|
| - Shorter overall reaction times means faster races means
| better records
|
| - The standard deviation of reaction times is smaller for
| sound than for sight, which means the reaction time is
| more fair to all
|
| [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456887/
| mattkrause wrote:
| Vision is amazingly sluggish. Turning an incoming photon
| into a nerve impulse involves a whole mess of slow (and
| fascinating) chemistry, just to leave the rod or code.
| Once it does that, the resulting signal bounces around
| the retina and then a huge portion of the brain before
| it's available for "action."
|
| The auditory system, on the other hand, is optimized for
| speed. It has a giant synapse (=connections between
| cells), called the Calyx of Held, that is specialized for
| extremely fast (sub-millisecond), reliable transmission
| between cells. They're really cool looking: https://www.e
| urekalert.org/multimedia/pub/213595.php?from=44...
| jfengel wrote:
| At least some swim meets use a light and a buzzer. I
| first encountered that many years ago at Gallaudet, a
| school for the deaf. I think that has become common at
| all swim races. It certainly makes sense to not exclude
| racers who can't hear.
|
| I did note at the time that the gunshot sound put an
| extra oomph into the start over a buzzer. No idea whether
| that actually made a difference to my time, but it sure
| got my heart rate up.
| tomr_stargazer wrote:
| My father was a world-class competitive swimmer and is a
| Deaf man. His stories about needing to rely on a visual
| cue when his hearing competitors benefited from the
| pistol sound were always fun -- as is the joy on his face
| when he narrates that he always beat them anyways.
| jlmcguire wrote:
| When I ran cross country in high school our coach always
| said to go on the sight of the smoke not the sound of the
| shot. This was when the starter was in front of the whole
| mass of runners. Not sure if it ever helped me given we
| were mass starting a race that lasted for 3ish miles.
| mattkrause wrote:
| If you were by yourself, that would only shave a fraction
| of a second off your 5k time. However, getting out in
| front of a big mass start also helps you avoid getting
| caught in "traffic", which can really bog you down.
| Supposedly wrote:
| Regarding the swimming issue, there is no underwater photo at
| the website which you linked, but one can google it, and it
| clearly shows that Phelps came in second. Arguments were made
| by Omega that the finish pad did not register Cavic's press on
| time since the force used was not enough.
|
| Moral of the story is that human error (be that of a mechanical
| nature) will always exist, but more care should be given in
| competitive sports. If you do not have the means to decide the
| winner, call it a tie, but if you do, even at the cost of a
| 350,000 photo/sec camera, then do it, but by all means do it
| correctly, because it might cost someone a gold medal at the
| Olympic games, and for the sake of people who put their life
| into competitive sports, this should not happen.
| parliament32 wrote:
| On the contrary.. Phelps is on the left here: https://www.si.
| com/.image/c_limit/MTY4MTg2NTcxMTk0MzEyMDY0/p...
| lcuff wrote:
| I agree with questioning the sanity ... There are likely all
| sorts of advantages and disadvantages that might exist at this
| level of granularity. For example who is on the inside at the
| start of the first curve of the race? Are the start and finish
| lines in exactly the same orientation (direction) and (as
| somebody else mentions) is everybody at the same distance from
| the starting gun? Speed of sound is finite. Call it a tie!
| sverhagen wrote:
| I don't think the competition really is: who's the fastest in a
| 216km race? Rather: who's strong enough to endure a 200km tour,
| and then still have the energy for a 16km race? I say this half
| jokingly only.
| crawdog wrote:
| This is really a team sport. There is a lot of strategy that
| goes into aligning the proper resources to win the race -
| From controlling the field, pulling in breakaways, supporting
| your teammates through mechanicals and still having the
| energy to finish out the final sprint. I would suggest
| catching the 30min breakdowns of the race on NBC Sports and
| the Latern Rouge on Youtube to better understand the race in
| a compressed format.
| davidw wrote:
| For the people here who are really in to bike racing, Chris
| Horner's "Butterfly Effect" videos are an interesting look
| at tactics.
| TwoBit wrote:
| Chris Horner could have been another Lemond or Armstrong
| if his career had played out better. He did win a grand
| tour though to prove that ability.
| davidw wrote:
| I occasionally see him around town here in Bend, which is
| kind of cool. His was... a difficult era in pro cycling.
| But putting that aside, his analysis of tactics is good,
| I think, and of interest for those looking to learn more
| about how a team runs things.
| vanderZwan wrote:
| I don't think this changes anything about the point being
| made by the person you were replying to though, unless I'm
| missing something
| xenocratus wrote:
| He's saying "it's not a 200km race, it's a 199km 'warmup'
| followed by a 1km sprint", so yes, it does change the
| perspective on how to judge how tight a race is
| TwoBit wrote:
| Many or most of the competitors would disagree it's not a
| race until KM 199. Only in boring flat races where the
| pack stays all together and there are no serious
| breakaways is that true.
| taejo wrote:
| I know next to nothing about competitive cycling (I'm a
| commuter and occasional touring cyclist) but would it be
| accurate to say it's a strategy game for something like
| 180 km interspersed with 20 km total of racing?
| LanceH wrote:
| I was in a conversation with some professional runners. A
| hobbyist in the same club asked, "when does it stop hurting?"
| They laughed and said, "It never stops. It's about how much
| you can make the other guy hurt."
|
| Cycling races are much the same with a team dynamic included.
| It's a matter of choosing between setting a pace that a
| sprint finisher can't follow over a long period, or
| sheltering a sprinter from the wind so he can put in maximal
| effort at the end of the race. There are all sorts of
| variations based on strength of team, weather, terrain, luck,
| politics between teams, race goals, etc...
| jkaptur wrote:
| The other famous quote in this regard is "It never gets
| easier, you just go faster."
| jdechko wrote:
| Rule #10, my second favorite rule only to Rule #5.
| nradov wrote:
| At the elite level of endurance sports everyone is in
| excellent condition and has optimal genetics. What really
| makes a winner is the ability to _suffer_.
| vbsteven wrote:
| That's the beauty of cycling isn't it? Sometimes the race-
| winning move is decided in a team car 150km from the line,
| and the next day it comes down to millimeters. This
| unpredictability is what keeps most viewers hooked to their
| TV sets for 6 hours on big race days.
| usrusr wrote:
| Sometimes, as in when it happens, people might still be
| talking about it decades later (I'm only slightly
| exaggerating)
|
| But all spectator sports seem to gain much their appeal
| from the imperfections that make them special. In road
| cycling, it's the imbalance of many hours of what computer
| gamers would call mostly cooperative PvE serving as a
| buildup for the few seconds of the finish (unless it's a
| solo, which is super attractive for the audience because
| it's rare, but would be rather boring if it wasn't).
| zappo2938 wrote:
| > 216.75km long race by someone who (possibly) won by 0.016
| seconds
|
| In cycling races that are not time trials it is disadvantaged
| to be in the lead until the last 0.016 seconds. The peleton in
| the video was quickly catching up to the three lead riders not
| because they were tired but rather because they were fighting
| to be in third position. It is just as much like a strategic
| game of chess as an endurance sport. Because of this, the game
| only works if a contender can win by a hair's length.
| zython wrote:
| In cycling you dont race the parcours you race your opponent,
| so the winner will do just as much work as is needed to beat
| his opponent.
| oconnor663 wrote:
| I think this is the key. The strategy that makes you most
| likely to beat your personal best, isn't the same as the
| strategy that makes you most likely to win the race. Races
| this close don't mean that the athletes were incredibly
| exactly matched, but that their racing strategies kept them
| close to each other.
| dropofwill wrote:
| To me at least the length of the race just makes the situation
| less likely to occur. The problem is still in play for a 4 km
| pursuit or in theory the transcontinental race (though the
| likelihood of a sprint finish is near 0).
|
| In general I think in sport we should use replay tech to
| eliminate errors that human judges _can_ make, not improve
| accuracy beyond what was possible for them to see (because
| fundamentally these are philosophically vague). And then just
| have rules for ties that are good for the sport: ties go to the
| runner in baseball, offsides go to the attacking player in
| soccer (I believe the dutch do something like this by using
| thicker lines for their VAR?), etc.
|
| But with cycling the whole game is decided by the finish, so I
| think that makes a bit harder to come up with a satisfying
| approach.
|
| I was curious what the actual rules are about calling ties.
| Apparently if there's no photo finish tech and the sprint
| between 2 riders can't be decided its called a "dead heat":
|
| > if the finish takes place on a road, the two riders will race
| against one another over a distance of 1000 m, from a standing
| start
|
| https://www.uci.org/docs/default-source/publications/practic...
| (page 26)
|
| Which sounds awesome to me. If it's a group of 3 or more they
| are just declared 'equals'.
|
| The rules for ties with photo finish tech (basically all pro
| races afaik) is kind of weird? All I could find was:
|
| > If, after all technical means available have been exhausted,
| it is still not possible to separate riders for one of the
| first three places at the world championships or Olympic Games,
| these riders shall each be awarded the placing in question. No
| award shall be made for the following placing, or, where there
| is a three-way tie, for the following two placings
|
| - Rule 2.3.043 in the UCI Road Race rulebook
|
| Not clear what that means for races like Amstel...
| kingosticks wrote:
| There's a arguably better, higher level writeup at
| https://cyclingtips.com/2021/04/making-sense-of-the-controve...
| which concludes:
|
| > The black line is a visual approximation of the placement of
| the finish, but the image from the photo finish camera is the
| true arbiter of the result - not the other way around. It's
| technical and it's a bit confusing, but it's clear-cut and the
| riders and officials are playing the same game with the same
| known set of rules.
|
| > According to UCI regulations, the photo finish verdict is
| final, because the finish line is what the photo finish says it
| is.
|
| Which makes most of the detective work here sadly pointless.
|
| Pidcock probably didn't need to tweet his take, in the same way
| he didn't need to post that ridiculous bogus 5k time!
| https://www.rouleur.cc/blogs/the-rouleur-journal/the-column-...
| Invictus0 wrote:
| If there are supposed to be two photo finish cameras, how can
| the photo finish be the true arbiter? The two cameras cannot
| possibly be perfectly aligned.
| kingosticks wrote:
| I'm not an expert but the UCI document labels it as "1 main
| camera, 1 opposite". So I would guess the "main" camera is
| the source of truth and the other is a backup?
|
| Either way, presumably both cameras ideally need to be
| aligned _to the line_ as stated. That should be possible and
| perfect alignment between the two cameras isn 't required. I
| can't see anywhere that it states the two cameras actually
| need to agree, isn't it fine providing one of them is used
| consistently.
| bagacrap wrote:
| this. Also the camera is intentionally not aligned to the black
| strip on the tarmac as tires are black and this would make it
| hard to see them.
| jrnvs wrote:
| Here's an interview with the photo operator, in Dutch:
| https://nos.nl/artikel/2377417-fotofinish-operator-amstel-go...
|
| Interviewer: Is it possible that the photo was taken a wee bit
| before the black line? Photo operator: I doubt it... I doubt it
| because we really took a good look if it's all been set up
| correctly.
| tinus_hn wrote:
| That's obviously wrong because if they had pointed at the black
| line, the background of the picture wouldn't have been the
| white part of the bar.
| sverhagen wrote:
| I operated the photo finish at the Amstel Gold Race for a few
| years, in the early 2000s, as well as at many other races in
| the Netherlands, Belgium and Germany. We weren't a constant
| presence at that event, as the association liked it better to
| either bring in their own people, or rather full-time
| professionals like the company that does La Tour de France. My
| boss at that time later sold his timing business to the guy who
| operated the photo finish this year (the one being
| interviewed).
|
| While all folks involved here take great pride in their work,
| the alignment of the camera just never got the attention it
| clearly deserved. No one ever did the math and they just
| assumed the difference wasn't significant. Also, people just
| liked it better to align the camera on the white part of the
| finish line, since it greatly improves the contrast of the
| capture. I am sure the equipment has improved, but for a long
| time, the only thing you were concerned about was contrast, a
| sudden change in weather (lighting) was known to, at times,
| render the entire operation useless. Particularly since we were
| a small operation with only one (photo-finish) camera. Plenty
| of times I had to climb up ladders and vans to make eleventh
| hour adjustments to the equipment, with the contestants already
| in sight.
|
| I feel super bad for the guy. To his defense, the
| responsibility lies with the UCI officials. To their defense,
| they do not check up on details like this. Until now, that is.
|
| I remember at least one other time where the broadcast camera
| (they also tend to have one exactly on the finish line) seemed
| in disagreement with our "official" photo finish results. That
| time, a simple shrug did the trick: "hey, photo finish, you
| know".
| tomglynch wrote:
| Hi Sverhagen, thanks for such an interesting insight. I do
| feel bad for the guy too, tough gig to have the cycling world
| analysing you just trying to do your job - especially when
| there are so many variables he'd have to account for.
|
| And 99.9% of the time it wouldn't make a difference, he's
| just very unlucky that this time it may have (or may not
| have, but either way it's brought a focus to the camera
| position).
|
| I see you're now a software engineer. How did you end up
| moving from photo-finish operations to software?
| getlawgdon wrote:
| I'm deeply familiar with FAT andamera systems in track and field.
| I often wonder if they are a relic but in track the timing can be
| trickier due to location of the torso. Wouldn't a transponder on
| a each headtube in the race potentially work better? They could
| talk communicate with sensors all around and in the finish line.
| tgtweak wrote:
| Taking "Internet Detective" to new and exotic levels.
| tomglynch wrote:
| Haha thank you - which part stood out to you?
| disillusioned wrote:
| Bro, literally all of it. What a great piece. Down to
| guesstimating the tire sizes, tracking down the line width,
| accounting for road camber, etc. Really enjoyed this.
| tomglynch wrote:
| Haha cheers! Enjoyed every moment of it (though I did spend
| quite a while on it all!)
| sachkris wrote:
| Nice write-up. Instead of these photo-finish cameras, would a
| piezoelectric sensor strip on the road (plus perhaps a regular
| camera) be a better solution to judge the winner in such cases?
| martyvis wrote:
| That would only work if the wheels were exactly the same
| diameter (assuming that the actual line is where the most
| forward part of the wheel crosses )
| mod wrote:
| No, because as I understand it we don't judge the winner from
| the base of the wheel, but rather the front of it.
| Luc wrote:
| But van Aert's front wheel was not even touching the road as he
| crossed the finish line...
| Workaccount2 wrote:
| I was thinking about this problem too, and realized that the
| photo-finish also provides placings for all the other
| contestants. Some other type of sensor might be able to more
| accurately place who was first, but could struggle greatly
| differentiating the pack of contestants behind them.
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